Beyond this dark opening lies a mystery tunnel that may have been Christopher Bechtler's gold mine. Some evidence points in that direction: by 1831, Bechtler was using a water-powered stamp mill of the type used to crush gold-bearing rock, the strongest indication that he was mining in rock. An 1837 visitor saw a tunnel following a vein, though he judged the rock not promising. Slots in the walls show that timbers once shored up the ceiling, and the room to the right of the entrance is of uncertain purpose, possibly a storage room for gold awaiting processing. From the entrance, the tunnel extends 80 feet before turning north for another 30 feet, where it is blocked by soil washed in over the decades. Pick marks remain clearly visible on the rocky walls. For many years after Bechtler's death, his property was sold and resold to speculators and mining companies, at one point selling for $1 million to New York investors. Hard-rock underground mining required more effort than surface mining: the rock had to be crushed, often with a water-powered stamp mill that lifted heavy iron hammers, and once pulverized, the heavier gold particles could be separated.